Download - 7. Reproduction in flowering plants - Part 2
Reproduction in Flowering Plants
Flower• Sexual reproductive structure
• Produces egg and sperm
• Fertilization takes place inside the flower
Pollen is produced in the male organs of the
flowers - anthers. Pollination occurs
when pollen is transferred from the
anthers to the female organs by wind or by animals. If the female
stigma is receptive to a pollen grain, the pollen
produces a pollen tube, which grows through the female tissue to the egg,
where fertilization takes place by the sperm nucleus.
Pistil*Stigma –top of the pistil,Sticky surface for pollen to
stick to*Style – connects the stigma
to the ovary*Ovary –contains ovules ( eggs)
Stamen*Anther – produces sperm
nuclei by meiosis. Sperm nuclei are enclosed by pollen grains.
*Filament – holds the anther up
Female reproductive organ
Male reproductive organ
Pollination
• Transfer of mature pollen grains from the anther to the stigma
-wind
-insects
-birds & other animals
• When a pollen grain lands on the stigma, it germinates and a pollen tube grows down through the style to an ovule (egg)
Fertilization• The sperm travels through the pollen tube to the
ovule. The sperm & egg fuse forming the zygote (fertilized egg) –this grows into the plant embryo (cells grow by mitosis)
*Self pollination –pollen from same flower
*Cross pollination – pollen from a different flower - more variation
• The ovary and zygote (fertilized ovule) develop and ripen.
*The ovule forms the seed and the ovary forms the fruit.
• A fruit is a ripened ovary
The plant embryo uses food stored in the cotyledon of the seed until it develops
leaves for photosynthesis
micropyle –opening in ovule where pollen tube attached, sperm entered
hilum –scar where ovule attached to ovary
radicle –embryonic root
Seedling
Epicotyl – grows above the cotyledons and gives rise to the leaves.
Hypocotyl –below the point of attachment of the cotyledon, develops into the stem.
Parts of a seed
• Dicot
• Monocot
Seed coat
Epicotyl
Cotyledons
Hypocotyl
Seed coatEndosperm
Epicotyl
Hypocotyl
RadicleCotyledon
Seed Germination
Monocot Dicot
Hypogeous
Epigeous
Radicle